Days after ripping Republicans for the political theater of holding a health care repeal vote, Democrats are planning their own bit of campaign messaging: a new push for legislation to force disclosure of political spending.

The Senate is expected to vote Monday night on whether to move forward with a bill to do just that, but Republicans are expected to lead a filibuster of the measure, as they have in the past. In fact, Democratic sources said they will have a majority for the bill but that they expect to be well short of the 60 votes needed to cut off debate. They also expect to lose one or two Members of their caucus on the vote.

Undeterred by the bill’s poor prospects, Rep. Chris Van Hollen (D-Md.), the sponsor of the House version of the bill, filed a discharge petition this week with hopes of forcing a House vote as well.

“This DISCLOSE Act will shine its light on the sources of the secret money polluting elections,” said Sen. Sheldon Whitehouse (D-R.I.), who was joined by Senate Rules and Administration Chairman Charles Schumer (D-N.Y.) and several colleagues at a Thursday press conference.

“This ‘new’ proposal once again disproportionately favors unions and is nothing more than a poorly veiled attempt to stifle political speech — Democrats’ strategy to win elections. Unfortunately, the Democratic leadership has delivered a Trojan horse,” said Rep. Dan Lungren (R-Calif.), chairman of the House Administration Committee.

But Van Hollen said the law could help Democrats fight “corporations that move jobs overseas to special tax havens, like the Cayman Islands, like Switzerland.” President Barack Obama’s campaign has attacked presumptive GOP presidential nominee Mitt Romney on outsourcing and for holding bank accounts in places such as the Cayman Islands and, at one point, Switzerland.

Still, Democrats say they’ve taken pains to ensure the bill does not exempt any left-leaning political groups, including removing several provisions that had drawn scrutiny.

“I have looked at this bill repeatedly, and there simply isn’t in it a separate standard for unions,” Whitehouse said. He added that he has “repeatedly invited” Republicans to identify the problem in the bill and to propose language that would fix it.

Also missing from the new version of a bill is a carefully crafted exemption for the National Rifle Association that appeared in a 2010 proposal. The gun rights group attacked the Senate version of the bill in a letter Thursday announcing its opposition.